Density-dependent and density-independent causes of extinction of a salamander population
Jaeger RG. 1980. Density-dependent and density-independent causes of extinction of a salamander population. Evolution. 34(4):617-621
Brief Description: This article documents and weighs the causes of extinction of salamander species in Shenandoah National Park Full Description: Previous studies showed that the Shenandoah salamander, Plethodon shenandoah, is confined to several dry talus slopes in the Blue Ridge Mountains of Virginia; it is competitively excluded by P. cinereus from moister areas of soil in forests. A 14-year census of the population densities of both species shows that a 28-day drought in 1970 did not affect the density of P cinereus, due to the buffering effect of its deep-soil habitat. However, P shenandoah suffered about 99% mortality during the drought. A population in one talus recovered to its pre-drought density in eight years. This was due to the patchy presence of soil in this talus, which prevented critical dehydration of a small fraction of the population. In another talus, which lacks patches of soil, the drought resulted in the extinction of the P. shenandoah population; no individuals have been found there over nine years since the drought. This demonstrates that interspecific competition acted as the density-dependent ultimate factor leading to extinction while a climatic perturbation acted as the density-independent proximate factor.
- Type
- Journal Article
- Authors
- Jaeger, Robert
- Units
- SHEN
- Keywords
- Animal Behavior, Animal Studies, Competition, Density, Extinction, Herpetology (Amphibians/Reptiles), Population, Research Report, Shenandoah Salamander (Plethodon shenandoah)